Keyword: optics
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MOYAA01 The LHC from Commissioning to Operation injection, luminosity, controls, ion 11
 
  • M. Lamont
    CERN, Geneva, Switzerland
  
  In 2011 the LHC moves from commissioning into the physics production phase with the aim of accumulating 1fb-1 by the end of 2011. The progress from commissioning to operation is described. Emphasis is put on the beam performance, but also on the performance of the different hardware systems. The role of collimation and machine protection is discussed, in view of the very high stored beam and magnet energy. Comment: Other invited presentations in this conference will cover the experience with beam instrumentation and the upgrade programmes.  
slides icon Slides MOYAA01 [7.410 MB]  
 
MOPC144 Autocorrelation Function and Power Spectrum of a Train of Quasiperiodic Sequence of Pulses electron, FEL, wakefield, free-electron-laser 415
 
  • E.M. Laziev, B. Grigoryan, V.M. Tsakanov
    CANDLE, Yerevan, Armenia
  • M. Movsisyan, D.L. Oganesyan
    YSU, Yerevan, Armenia
  
  The statistical relationship of the autocorrelation function and spectrum of a train of quasi-periodic sequence of pulses having a time jitter of the repetition rate is obtained. Presented the accordance of autocorrelation function as well as power spectrum of the bounded quasi-periodic sequence of pulses and timing jitter of their repetition rate. The results can be used at the measurements of timing jitter of a train of electron bunches.  
 
MOPS009 Probing Intensity Limits of LHC-type Bunches in the CERN SPS with Nominal Optics emittance, injection, single-bunch, extraction 610
 
  • B. Salvant, G. Adrian, D.J. Allen, O. Andujar, T. Argyropoulos, J. Axensalva, J. Baldy, H. Bartosik, S. Cettour Cave, F. Chapuis, J.F. Comblin, K. Cornelis, D.G. Cotte, K. Cunnington, H. Damerau, M. Delrieux, J.L. Duran-Lopez, A. Findlay, J. Fleuret, F. Follin, P. Freyermuth, H. Genoud, S.S. Gilardoni, A. Guerrero, S. Hancock, K. Hanke, O. Hans, R. Hazelaar, W. Höfle, L.K. Jensen, J. Kuczerowski, Y. Le Borgne, R. Maillet, D. Manglunki, S. Massot, E. Matli, G. Metral, B. Mikulec, E. Métral, J.-M. Nonglaton, E. Ovalle, L. Pereira, F.C. Peters, A. Rey, J.P. Ridewood, G. Rumolo, J.L. Sanchez Alvarez, E.N. Shaposhnikova, R.R. Steerenberg, R.J. Steinhagen, J. Tan, B. Vandorpe, E. Veyrunes
    CERN, Geneva, Switzerland
  
  Some of the upgrade scenarios of the high-luminosity LHC require large intensity per bunch from the injector chain. Single bunch beams with intensities of up to 3.5 to 4·1011 p/b and nominal emittances were successfully produced in the PS Complex and delivered to the SPS in 2010. This contribution presents results of studies with this new intense beam in the SPS to probe single bunch intensity limitations with nominal gamma transition. In particular, the vertical Transverse Mode Coupling Instability (TMCI) threshold with low chromaticity was observed at 1.6·1011 p/b for single nominal LHC bunches in the SPS. With increased vertical chromaticity, larger intensities could be injected, stored along the flat bottom and accelerated up to 450 GeV/c. However, significant losses and/or transverse emittance blow up were then observed. Longitudinal and transverse optimization efforts in the PSB, PS and SPS were put in place to minimize this beam degradation and succeeded to obtain single 2.3·1011 p/b LHC type bunches with satisfying parameters at extraction of the SPS.  
 
MOPS010 Experimental Studies with Low Transition Energy Optics in the SPS emittance, injection, single-bunch, damping 613
 
  • H. Bartosik, T. Argyropoulos, T. Bohl, S. Cettour Cave, K. Cornelis, J. Esteban Muller, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, J. Wenninger
    CERN, Geneva, Switzerland
  
  The optics of the SPS can be tuned to lower transition energy such that the slippage factor at injection is raised by a factor of almost 3. From theory, an increase of the intensity thresholds for transverse mode coupling, longitudinal coupled bunch and longitudinal instabilities due to the loss of Landau damping can be expected. In this paper, experimental studies in the SPS with single bunches of protons with intensities of up to 3.5·1011 p/b on the flat bottom and at 450 GeV/c are presented. Longitudinal instabilities were studied with LHC-type beams with 50~ns spacing and injected intensities up to 1.8·1011 p/b. The measurements address the increase of intensity thresholds and the achievable transverse emittances in the new low gamma transition optics with respect to the nominal SPS optics. The obtained results are compared with numerical simulations.  
 
MOPS011 Impact of Low Transition Energy Optics to the Electron Cloud Instability of LHC Beams in the SPS electron, simulation, synchrotron, emittance 616
 
  • H. Bartosik, E. Benedetto, K.S.B. Li, Y. Papaphilippou, G. Rumolo
    CERN, Geneva, Switzerland
  
  One of the main limitations for high intensity multi-bunch LHC proton beams in the SPS is imposed by electron cloud instabilities. A new optics of the SPS with lower transition energy was implemented and successfully tested in machine studies. The significant increase of the slippage factor that it provides at injection energy results in the expected increase of the single bunch instability thresholds. In this paper, the impact of this new optics on the electron cloud instability threshold is estimated by using numerical simulations, taking into account the change of the optics functions and the faster synchrotron motion due to the reduced transition energy.  
 
MOPS012 Optics Considerations for Lowering Transition Energy in the SPS injection, resonance, emittance, lattice 619
 
  • H. Bartosik, G. Arduini, Y. Papaphilippou
    CERN, Geneva, Switzerland
  
  Beam stability for high intensity LHC beams in the SPS can be improved by increasing the slippage factor, i.e. reducing the transition energy. In this paper, possible ways of modifying the optics of the SPS for lower transition energy are reviewed. In particular, a threefold increase of the slippage factor at injection can be achieved by decreasing the integer part of the tunes by 6 units. The properties of this new low-transition optics are compared with the nominal SPS optics, including working point and resonance behavior. Possible limitations are discussed.  
 
MOPS031 Beam Dynamics Redesign of IFMIF-EVEDA RFQ for a Larger Input Beam Acceptance rfq, emittance, focusing, solenoid 670
 
  • M. Comunian, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  
  For the IFMIF-EVEDA RFQ, a very challenging project of a deuteron CW RFQ at 175 MHz from 0.1 MeV to 5 MeV with 125 mA of current, the input beam characteristics are very important. A lower focusing force in the first part of the RFQ as beam implemented in order to reduce the requirements of the input beam. In the article a full description of the new design will be reported with the changes in the RFQ performances.  
 
MOPS051 Modeling of the Beam Break Up Instability for BERLinPro* cavity, linac, solenoid, HOM 718
 
  • Y. Petenev, A.V. Bondarenko, A.N. Matveenko
    HZB, Berlin, Germany
  
  Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current low emittance beam. In this work the threshold current of the Beam Break Up (BBU) instability was calculated for the BERLinPro. The comparison of two 100 MeV linacs based on different type of superconducting cavities is made. Different methods of BBU suppression are investigated (e.g. the influence of solenoid, pseudo-reflector and quadruple triplets in the linac structure on the BBU threshold).  
 
MOPZ031 Multipass Muon RLA Return Arcs based on Linear Combined-function Magnets linac, dipole, quadrupole, lattice 868
 
  • V.S. Morozov, S.A. Bogacz, Y. Roblin
    JLAB, Newport News, Virginia, USA
  • K.B. Beard
    Muons, Inc, Batavia, USA
  
  Funding: Supported in part by US DOE STTR Grant DE-FG02-08ER86351. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Recirculating Linear Accelerators (RLA) are an efficient way of accelerating short-lived muons to the multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. In this paper we present a design of a two-pass RLA return arc based on linear combined function magnets, in which both charge muons with momenta different by a factor of two are transported through the same string of magnets. The arc is composed of 60°-bending symmetric super cells allowing for a simple arc geometry closing. By adjusting the dipole and quadrupole components of the combined-function magnets, each super cell is designed to be achromatic and to have zero initial and final periodic orbit offsets for both muon momenta. Such a design provides a greater compactness than, for instance, an FFAG lattice with its regular alternating bends and is expected to possess a large dynamic aperture characteristic of linear-field lattices. 		 
 
TUPC016 Status of the ATF2 Lattices lattice, quadrupole, sextupole, multipole 1027
 
  • E. Marin, R. Tomás
    CERN, Geneva, Switzerland
  • P. Bambade
    LAL, Orsay, France
  • T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • A. Seryi
    JAI, Oxford, United Kingdom
  • G.R. White, M. Woodley
    SLAC, Menlo Park, California, USA
  
  The latest status for the ATF2 Nominal and Ultra-low beta lattices designs obtained to minimize the detrimental effect of the measured multipoles are presented in this paper. A set of correction knobs for the most important aberrations at the IP have been obtained for both lattices in order to perform the tuning under realistic imperfections. Starting from the tuned ATF2 Nominal lattice a squeeze sequence reducing betay is performed to reach the ultra-low beta lattice. Tuning results are shown for both options.  
 
TUPC049 Optics considerations for the Delay Loop in the CLIC Damping Rings Complex dipole, quadrupole, emittance, damping 1108
 
  • P. Zisopoulos, F. Antoniou, H. Bartosik, Y. Papaphilippou
    CERN, Geneva, Switzerland
  
  For the recombination of the two trains coming from the CLIC damping rings, a delay loop will be used in order to obtain the nominal 0.5~ns bunch spacing. The optics design of the loop is based upon an isochronous ring, in order to preserve the longitudinal beam distribution. Analytical expressions for achieving isochronous conditions in high order for Theoretical Minimum Emittance cells are obtained. A parametrisation of the quadrupole settings for achieving these conditions is presented, along with general considerations regarding the choice of bending magnet characteristics.  
 
TUPC054 LHeC ERL Design and Beam-dynamics Issues linac, emittance, HOM, cavity 1120
 
  • S.A. Bogacz, I. Shin
    JLAB, Newport News, Virginia, USA
  • D. Schulte, F. Zimmermann
    CERN, Geneva, Switzerland
  
  We discuss machine and beam parameter choices for a Linac-Ring option of the Large Hadron electron Collider (LHeC) based on the LHC. With the total wall-plug power limited to 100 MW and a target current of about 6 mA the desired luminosity of 1033 cm-2 s-1 can be reached, providing one exploits unique features of the Energy Recovery Linac (ERL). Here, we describe the overall layout of such ERL complex located on the LHC site. We present an optimized multi-pass linac optics enabling operation of the proposed 3-pass Recirculating Linear Accelerator (RLA) in the Energy Recovery mode. We also describe emittance preserving return arc optics architecture; including layout and optics of the arc switch-yard. Furthermore, we discuss importance of collective effects such as: beam breakup in the RLA, as well as ion accumulation, with design-integrated mitigation measures, and the electron-beam disruption in collision. Finally, a few open questions are highlighted.  
 
TUPC069 Bunch Length Measurements from the Incoherent Synchrotron Radiation Fluctuation at SOLEIL radiation, undulator, electron, photon 1159
 
  • M.-A. Tordeux, F. Dohou, M. Labat, O. Marcouillé
    SOLEIL, Gif-sur-Yvette, France
  
  Bunch length measurements can be made by analysing the pulse to pulse intensity fluctuation of the incoherent synchrotron radiation as it has been reported elsewhere*. Such a method has been tested at SOLEIL for picosecond bunch durations, at several wavelengths and bandwidths in the visible range, using an avalanche photodiode. Thanks to the low-alpha optics the lengths of 10 μA bunches as short as 3 ps have been measured in good agreement with the streak camera results. We first used the radiation from a bending magnet, and then from a HU640 undulator that enhances the photon flux. Moreover, taking advantage of using the radiation from an undulator, we show that the method can still be used when the number of spikes emitted by the electron bunch is reduced to a few hundreds. This could be of interest for bunch length measurements of X-ray SASE FELs. Furthermore, we intend to use a single crystal diamond detector in order to perform these measurements in the X-ray range.
* F. Sannibale et al., "Absolute bunch length measurements by incoherent radiation fluctuation analysis", PRST AB 12, 032801 (2009).
 		 
 
TUPC085 Observation of Microwave Radiation using Low-cost Detectors at the ANKA Storage Ring radiation, synchrotron, storage-ring, vacuum 1203
 
  • V. Judin, N. Hiller, A. Hofmann, E. Huttel, B. Kehrer, M. Klein, S. Marsching, A.-S. Müller, M.J. Nasse, N.J. Smale
    KIT, Karlsruhe, Germany
  • F. Caspers
    CERN, Geneva, Switzerland
  • P. Peier
    PSI, Villigen, Switzerland
  
  Funding: Work supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320
Synchrotron light sources emit Coherent Synchrotron Radiation (CSR) for wavelengths longer than or equal to the bunch length. At most storage rings CSR cannot be observed because the waveguide cuts off radiation with long wavelengths. There are different approaches for shifting the CSR to shorter wavelengths that can propagate through the beam pipe, e.g.: The accelerator optics can be optimized for a low momentum compaction factor, thus reducing the bunch length. Alternatively, laser slicing can modulate substructures on long bunches. Both techniques extend the CSR spectrum to shorter wavelengths, so that CSR is emitted at wavelengths above the waveguide cut off. Usually fast detectors, like superconducting bolometer detector systems or Schottky barrier diodes, are used for observation of dynamic processes in accelerator physics. In this paper, we present observations of microwave radiation at ANKA using an alternative detector, a LNB (Low Noise Block) system. These devices are usually used in standard TV-SAT-receivers and are very cheap. We determined the time response of LNBs to be below 100 ns. The sensitivity of LNBs is optimized to detect very low intensity "noise-like" signals. 		 
 
TUPC158 Micron-scale Laser-wire at the ATF-II at KEK Commissioning and Results laser, electron, photon, diagnostics 1401
 
  • L.J. Nevay, G.A. Blair, S.T. Boogert, L. Corner, L.C. Deacon, V. Karataev, R. Walczak
    JAI, Oxford, United Kingdom
  • A.S. Aryshev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  
  We present the first results from the commissioning of the upgraded laser-wire experiment at the Accelerator Test Facility 2 (ATF2) at KEK. A new laser transport line and beam diagnostics were used to collide 150 mJ, 167 ps long laser pulses with 1.28 GeV, 30 ps long electron bunches to measure the vertical transverse size. Additionally, a new detector was installed with a reduced area for lower background. Initial scans showing a convoluted beam size of 19.2 ± 0.2 microns were used to tune the electron beam optics and reduce this down to 8.1 ± 0.1 microns. Laser pulse energy and charge dependency were investigated showing a linear relationship in both with a minimum laser energy of 20 mJ required for observable signal with this laser and setup.  
 
TUPO029 Status of the BERLinPro Optics Design emittance, linac, vacuum, electron 1500
 
  • A.N. Matveenko, M. Abo-Bakr, A.V. Bondarenko, A. Jankowiak, J. Knobloch, B.C. Kuske, Y. Petenev
    HZB, Berlin, Germany
  
  Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current (100 mA) low emittance beam (1 mm•mrad normalized), as required for future ERL-based synchrotron light sources. Given the flexibility ERLs provides, a short bunch operation mode will also be investigated. Current optics was designed to allow of low emittance and short bunch operation modes. Optics is flexible to suppress BBU and minimize CSR effects. Estimation of impact of ion accumulation, wake fields, halo and chromatic aberrations is given. Requirements for beam diagnostic system, alignment accuracy and power supply stability are investigated.  
 
TUPS026 Specification of New Vacuum Chambers for the LHC Experimental Interactions vacuum, alignment, impedance, injection 1584
 
  • R. Veness, R.W. Assmann, A. Ball, A. Behrens, C. Bracco, G. Bregliozzi, R. Bruce, H. Burkhardt, G. Corti, M.A. Gallilee, M. Giovannozzi, B. Goddard, D. Mergelkuhl, E. Métral, M. Nessi, W. Riegler, J. Wenninger
    CERN, Geneva, Switzerland
  • N. Mounet, B. Salvant
    EPFL, Lausanne, Switzerland
  
  The apertures for the vacuum chambers at the interaction points inside the LHC experiments are key both to the safe operation of the LHC machine and to obtaining the best physics performance from the experiments. Following the successful startup of the LHC physics programme the ALICE, ATLAS and CMS experiments have launched projects to improve physics performance by adding detector layers closer to the beam. To achieve this they have requested smaller aperture vacuum chambers to be installed. The first periods of LHC operation have yielded much information both on the performance of the LHC and the stability and alignment of the experiments. In this paper, the new information relating to the aperture of these chambers is presented and a summary is made of analysis of parameters required to safely reduce the vacuum chambers apertures for the high-luminosity experiments ATLAS and CMS.  
 
TUPS060 Designing, Integrating, and Coordinating Installation of MedAustron survey, synchrotron, extraction, alignment 1671
 
  • B. Nicquevert, C. Hauviller
    CERN, Geneva, Switzerland
  • M. Benedikt, B. Nicquevert
    EBG MedAustron, Wr. Neustadt, Austria
  
  Funding: CERN, Geneva, Switzerland EBG MedAustron, Wiener Neustadt, Austria
"Give me a layout good enough and a building to place it, and I will install your accelerator". To paraphrase Archimedes, this is the role attributed to Integration team in MedAustron project. Starting with the optics layout and a building sketch, the integration work consists of a series of activities, interlinked in a complex manner. First the design and integration of the accelerator: list items, define geometrical envelopes with interfaces, put them in position in CAD, identify conflicts, define input for items design and infrastructure. Then the various equipment is procured: verify and validate design data, follow-up manufacturing, fiducialize equipment, build supports. Lastly global installation: check equipped building, define survey framework, install and pre-align equipment on supports, move assemblies to their final location, survey actual position and adjust to theoretical position. The whole chain of operations from a layout to a real beam in MedAustron is illustrated. The help from item-driven data management is emphasized. Grouping all activities within a single team favors interactions between stakeholders and consistency of activities. 		 
 
TUPZ001 90 m Optics Commissioning proton, coupling, injection, scattering 1795
 
  • S. Cavalier
    LAL, Orsay, France
  • H. Burkhardt, M. Fitterer, G.J. Müller, S. Redaelli, R. Tomás, G. Vanbavinckhove, J. Wenninger
    CERN, Geneva, Switzerland
  
  Special β* = 90 m optics have been developed for the two very high luminosity insertions of the LHC, as a first step towards to allow for very low angle precision measurements of the proton-proton collisions in the LHC. These optics were developed to be compatible with the standard LHC injection and ramp optics. The target value of β* = 90 m is reached by an un-squeeze from the injection β* = 11 m. We describe the implementation of this optics in the LHC and the first experience in the commissioning of these optics.  
 
TUPZ002 90 m β* Optics for ATLAS/ALFA emittance, luminosity, scattering, quadrupole 1798
 
  • S. Cavalier, P.M. Puzo
    LAL, Orsay, France
  • H. Burkhardt
    CERN, Geneva, Switzerland
  • A. Peskov
    NNGU, Nizhny Novgorod, Russia
  
  We describe a high β* optics developed for the ATLAS detector at the LHC interaction regions (IR1), Roman Pots have been installed 240 m left and right of IR1 to allow to measure the absolute luminosity and the total elastic cross section for ATLAS with ALFA (Absolute Luminosity for ATLAS). Ultimately, it is planned to preform these measurements at a very high β* of 2625 m. Here we describe a new, intermediate β* = 90 m optics, which has been optimized for compatibility with the present LHC running conditions. We described the main features and expected performance of this optics for ALFA.  
 
TUPZ006 Aperture Determination in the LHC Based on an Emittance Blowup Technique with Collimator Position Scan beam-losses, emittance, injection, storage-ring 1810
 
  • R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, S. Redaelli, F. Schmidt, R. Tomás, J. Wenninger, D. Wollmann
    CERN, Geneva, Switzerland
  • M. Alabau
    IFIC, Valencia, Spain
  
  A new method to determine the LHC aperture was proposed. The new component is a collimator scan technique that refers the globally measured aperture limit to the shadow of the primary collimator, expressed in σs of rms beam size. As a by-product the BLM response to beam loss is quantified. The method is described and LHC measurement results are presented.  
 
TUPZ009 LHC Machine Protection against Very Fast Crab Cavity Failures cavity, luminosity, betatron, emittance 1816
 
  • T. Baer, R. Tomás, J. Tückmantel, J. Wenninger, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Baer
    Uni HH, Hamburg, Germany
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  
  For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is essential to compensate the geometric luminosity loss due to the crossing angle. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a CC quench), the voltage and/or phase of a CC can change significantly with a fast time constant of the order of a LHC turn. This can lead to large, global betatron oscillations of the beam. Against the background of machine protection, the influence of a CC failure on the beam dynamics is discussed. The results from dedicated tracking studies, including the LHC upgrade optics, are presented. Necessary countermeasures to limit the impact of CC failures to an acceptable level are proposed.  
 
TUPZ011 LHC Collimation with a Reduced Beam Pipe Radius in ATLAS simulation, collimation, scattering, background 1822
 
  • R. Bruce, R.W. Assmann
    CERN, Geneva, Switzerland
  
  Based on SixTrack simulations, we investigate the effect from collimation of a reduced beam pipe in the ATLAS experiment in the LHC. Several running scenarios are studied with range of different beam pipe radii and in each case we conclude on the minimum allowed aperture, which does not cause beam losses inside the detectors.  
 
TUPZ013 Calculation Method for Safe Beta* in the LHC luminosity, emittance, collimation, injection 1828
 
  • R. Bruce, R.W. Assmann, W. Herr, D. Wollmann
    CERN, Geneva, Switzerland
  
  One way of increasing the peak luminosity in the LHC is to decrease the beam size at the interaction points by squeezing to smaller values of beta*. The LHC is now in a regime where safety and stability determines the limit in beta*, as opposed to traditional optics limits. In this paper, we derive a calculation model to determine the safe beta*-values based on collimator settings and operational stability of the LHC. This model was used to calculate the settings for the LHC run in 2011. It was found that beta* could be decreased from 3.5 m to 1.5 m, which has now successfully been put into operation.  
 
TUPZ026 Alternative Working Point(s) at Injection for the LHC injection, coupling, quadrupole, emittance 1861
 
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
At present, the LHC operates with a different fractional tunes at injection and at collision energy due to improved dynamic aperture indicated by tracking studies. Therefore, a tune swing crossing the 10th order resonance is needed during the beta-squeeze. A new proposal to alter the working point to collision tunes already at injection and during an energy ramp is foreseen to avoid the tune jump. Simulations and measurements of the optics along with the beam emittances and lifetime are compared to the nominal injection tunes. Feasibility for a working point close to the 1/2 integer is also attempted. 		 
 
TUPZ027 Beta* Measurement in the LHC Based on K-modulation quadrupole, luminosity, simulation, lattice 1864
 
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
Accurate knowledge of the collision point optics is crucial to equalize the luminosities at the different experiments. K-modulation was successfully applied at several accelerators for measuring the lattice beta functions. In the LHC, it was proposed as an alternative method to compute the beta* at the collision points. Results of beta* measurements in the LHC based on the K-modulation technique are presented with comparisons to nominal segment-by-segment method. 		 
 
TUPZ028 Beam Based Optimization of the Squeeze at the LHC feedback, beam-losses, simulation, controls 1867
 
  • X. Buffat
    EPFL, Lausanne, Switzerland
  • M. Lamont, S. Redaelli, J. Wenninger
    CERN, Geneva, Switzerland
  
  The betatron squeeze is a critical operational phase for the LHC because it is carried out at top energy, with the maximum stored energy and with reduced aperture margins in the superconducting triplets. A stable operation with minimum beam losses must be achieved in order to ensure a safe and efficient operation. The operational experience at the LHC showed that this is possible. The operation in 2010 is reviewed. In particular, orbit, tune and chromaticity measurements are investigated and correlated to beam losses. Different optimizations are then proposed towards a more efficient and robust operation. The improvements obtained for the operation in 2011 are presented.  
 
TUPZ030 Simulation of Linear Beam Parameters to Minimize the Duration of the Squeeze at the LHC simulation, controls, collider, acceleration 1873
 
  • X. Buffat
    EPFL, Lausanne, Switzerland
  • G.J. Müller, S. Redaelli, M. Strzelczyk
    CERN, Geneva, Switzerland
  
  The betatron squeeze allows to increase the luminosity of a collider by reducing the β function at the interaction points. This operation has shown to be very critical in previous colliders. In this state of mind, the squeezing was performed extremely safely during the first year of operation of the Large Hadron Collider, at the expense of the duration of the process. As the turnaround time is a relevant parameter for the integrated luminosity, a squeeze of shorter duration is proposed for 2011 and further. MadX simulation of linear beam parameters based on settings extracted from the LHC control system are used to justify the proposal. Further optimization of the squeeze setting generation is also discussed.  
 
TUPZ034 Impact of Arc Phase Advance on Chromatic Optics in RHIC quadrupole, injection, ion, proton 1885
 
  • R. Calaga, R. Miyamoto, G. Robert-Demolaize, S.M. White
    BNL, Upton, Long Island, New York, USA
  • R. De Maria, R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work is partially supported by the US Department of Energy through the LHC Accelerator Research program (LARP).
The phase advance between the two interaction points in RHIC is optimized for dynamic aperture for a initial design beta-star. This may not hold true as RHIC presently operates with a considerably reduced beta-star. Additionally the reduction of the available beam aperture due to an enlarged chromatic beta-beating is evident. Results from phase advance scans between the two IPs to reduce the chromatic beta-beating in model and measurements are presented. Impact on the single beam lifetime and momentum aperture is compared to the nominal optics. 		 
 
WEOAA03 Approach to a Start-to-end Simulation of 2-loop Compact Energy Recovery Linac electron, simulation, emittance, linac 1909
 
  • M. Shimada, K. Harada, Y. Kobayashi, T. Miyajima, N. Nakamura, S. Sakanaka
    KEK, Ibaraki, Japan
  • R. Hajima
    JAEA, Ibaraki-ken, Japan
  
  Transport of an extreme low emittance electron beam is critical issue in an energy recovery linac. In particlar, the space charge effect on an electron bunch in the injector with lower than 5 - 10 MeV induces a large emittance growth. To suppress the emittance growth by such as an optimization of the solenoid magnets, a nonlinear effect should be clarified by a three dimensional tracking simulation. The cons is that it consumes a enormous simulation time. The approach is not suitable for a double loop circulation because the simulation time depends on the transport length. Therefore the beam dynamics and optics are calculated by a start-to-end (S2E) simulation, in which the simulation code is switched after the full acceleration. We used 'general particle tracking (GPT)' for injector electron beam and 'elegant' for a circulator electron beam.  
slides icon Slides WEOAA03 [3.951 MB]  
 
WEYB01 Diagnostics for Ultra-low Emittance Beams laser, polarization, radiation, emittance 1959
 
  • J.W. Flanagan
    KEK, Ibaraki, Japan
  
  The achievement in recent years of beams with vertical emittance of a few pico-meters in a number of electron storage rings has presented challenges for diagnostics capable of beam size measurements in this regime. A number of different approaches have been developed for various machines (e.g. laser wire; interferometer; Shintake monitor; coded aperture; compound refractive lens). This presentation will review and compare the different methods, and discuss their strengths, weaknesses, ultimate limitations, and the situations where they might be appropriate; and consider possible future directions.  
slides icon Slides WEYB01 [2.553 MB]  
 
WEIB01 Chasing Femtoseconds – How Accelerators Can Benefit from Economies of Scale in Other Industries laser, scattering, polarization, controls 1973
 
  • M. Vidmar, J. Tratnik
    University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia
  • P.L. Lemut
    COBIK, Solkan, Slovenia
  
  Building accelerators we frequently push the limits of what is possible in terms of performance. When trying to solve a very challenging engineering problem, we normally resort to specialization; we narrow our focus. This talk suggests a possible alternative path. Huge benefits and great results can be achieved by combining creative ideas and approaches with ideas and solutions borrowed from the economies of scale like telecommunications. The aim of the talk is to show possibilities for combining ideas, technologies and components from different industries into innovative products.  
slides icon Slides WEIB01 [0.799 MB]  
 
WEPC004 Comparison of the Action and Phase Analysis on LHC Orbits with Other Techniques quadrupole, interaction-region, coupling, simulation 2004
 
  • J.F. Cardona
    UNAL, Bogota D.C, Colombia
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: DIB-Universidad Nacional de Colombia
Recently acquired turn-by-turn data of the LHC is analyzed using the action and phase jump technique. The results of this analysis show a visible variation of the action and phase plots at the interaction regions from which optic error estimations can be done. In this paper error estimations will be presented and comparisons with other existing techniques in the LHC, such as the recently implemented Segment-by-segment technique, will be discussed. 		 
 
WEPC011 Ion Optical Design of the Low Energy Ion Beam Facility at IUAC ion, ECR, quadrupole, target 2025
 
  • A. Mandal, D. Kanjilal, S. Kumar, G. Rodrigues
    IUAC, New Delhi, India
  
  A Low Energy Ion Beam Facility (LEIBF) using fully permanent magnet ECR ion source (Nanogan) has been installed at Inter University Accelerator Centre (IUAC), New Delhi for fundamental research on Atomic and Molecular Physics, and Material Science. The accelerator consists of an ECR ion source, 400 kV accelerating column and an analyzing-cum switching magnet with three beam ports at 75, 90 and 105 degrees. The complete ion optics from ECR ion source to the target has been simulated using TRANSPORT* and GICOSY** ion optics codes. The ions from the ECR source are typically extracted at 15 kV which are further accelerated by 400 kV accelerating column. The analyzing cum switching magnet has been designed to analyze different beams and to switch in a particular beam line. It is a H shaped dipole magnet having pole gap of 65 mm, maximum magnetic field of 1.5 T and radius of 529 mm for 90 degree bend. The entrance and exit edge angles for three beam lines have been optimized to obtain double focus in all beam lines. The beam is further transported to target locations using electrostatic quadrupole triplet. The details of ion optics will be presented in the paper.
* K.L. Brown, D.C. Carey, Ch. Iselin and F. Rothacker: Transport, See yellow reports CERN 73-16 (1973) & CERN 80-04 (1980).
** H.Weick, GICOSY homepage, http://www-linux.gsi.de/~weick/gicosy/. 		 
 
WEPC024 LOCO in the ALBA Storage Ring quadrupole, dipole, coupling, storage-ring 2055
 
  • G. Benedetti, D. Einfeld, Z. Martí, M. Muñoz
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
  
  ALBA is a 3 GeV 3rd generation light source which achieved first stored beam in February 2011, and will be commissioned during 2011. The ring comprises of 112 independent quadrupoles grouped in 14 families and 32 combined gradient dipoles powered in series. This paper reviews the process of recovering the design lattice and the symmetry of the machine, and the effects on orbit and lifetime. The main tool employ for this has been the LOCO implementation provided in the Matlab MiddleLayer. First results shows that the main effect on the symmetry is the difference between bending magnets. As this effect can not be compensated locally at present at the bendings, a global optics correction using all the quadrupoles is used.  
 
WEPC028 Record Low Beta-beat of 10% in the LHC injection, hadron, quadrupole, collider 2061
 
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  • M. Aiba
    PSI, Villigen, Switzerland
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  
  During the 2011 LHC run several measurements and correction campaigns were conducted. As a result a peak beta-beat of 10% level was achieved. This level, well below the specified tolerances of the LHC, improves the aperture margins and helps minimize the luminosity imbalance between the different experiments. A combination of local corrections at the insertion regions and an overall global correction were used to achieve this record low beta-beat. The sequence of the optics corrections and stability along the 2011 run are reported.  
 
WEPC029 Accuracy of the LHC Optics Measurement based on AC Dipoles dipole, simulation, quadrupole, focusing 2064
 
  • R. Miyamoto, R. Calaga
    BNL, Upton, Long Island, New York, USA
  • R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The tight tolerances in the LHC requires optics measurement with very good accuracy. Therefore, AC dipoles are employed as the primary devices to measure the LHC optics. The accuracy of the measurement is mainly determined by the length of the coherent signal, signal-to-noise ratio of the measurement, and the data processing to effectively suppress the noise. This paper presents numerical and experimental studies of how these factors affect the accuracy of the LHC optics measurement using the AC dipoles. 		 
 
WEPC030 Measurement of Coupling Resonance Driving Terms in the LHC with AC Dipoles dipole, kicker, quadrupole, resonance 2067
 
  • R. Miyamoto, R. Calaga
    BNL, Upton, Long Island, New York, USA
  • M. Aiba
    PSI, Villigen, Switzerland
  • R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
Transverse betatron coupling in the LHC is measured from Fourier analysis of turn-by-turn beam oscillations excited by AC dipoles. The use of the AC dipole for optics measurements induces a small systematic error which can be corrected with an appropriate data interpretation. An algorithm to apply this correction to the measurement of the coupling resonance driving terms is developed for the first time. This paper will review this new algorithm and present results of its application to the LHC. 		 
 
WEPC031 Optics Corrections at RHIC dipole, betatron, proton, quadrupole 2070
 
  • G. Vanbavinckhove
    CERN, Geneva, Switzerland
  • M. Bai, G. Robert-Demolaize
    BNL, Upton, Long Island, New York, USA
  
  Excessive beta-beat, deviation of measured beta function from the calculated beta functions based on an model, in high energy colliders can lead to large deviation of beta function at collision point as well as other adverse effects. The segment-by-segment technique was successfully demonstrated in the LHC operation for reducing the beta-beat. It was then applied to RHIC polarized proton operation in 2011. This paper reports the experimental results of optics correction at RHIC. Future plan is also presented.  
 
WEPC032 First Measurements of Higher Order Optics Parameters in the LHC simulation, resonance, injection, kicker 2073
 
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  • M. Aiba
    PSI, Villigen, Switzerland
  • R. Bartolini
    Diamond, Oxfordshire, United Kingdom
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • M. Giovannozzi, F. Schmidt, R. Tomás
    CERN, Geneva, Switzerland
  • E.H. Maclean
    JAI, Oxford, United Kingdom
  
  Higher order effects can play an important role in the performance of the LHC. Lack of knowledge of these parameters can increase the tune footprint and compromise the beam lifetime. First measurements of these parameters at injection and flattop have been conducted. Detailed simulations are compared to the measurements together with discussions on the measurement limitations.  
 
WEPC037 An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade luminosity, insertion, sextupole, quadrupole 2088
 
  • S.D. Fartoukh
    CERN, Geneva, Switzerland
  
  A novel optics concept has been invented and developed in the context of the LHC Upgrade studies. It offers an incredibly powerful and flexible machinery in order to squeeze beta* in a symmetric or asymmetric way (so-called “round” or “flat” optics, respectively), while perfectly controlling the chromatic aberrations induced (off-momentum beta-beating, non-linear chromaticity, spurious dispersion due to the crossing angles). The basic principles of the scheme are described and a specific path for the LHC upgrade is built accordingly, only relying on the existing and well-characterized LHC-like technology, and based on the production of flat collision optics with very small beta* (7.5 cm) in the plane perpendicular to the crossing plane.  
 
WEPC042 Implementation of Double Mini-beta Optics at the Diamond Light Source injection, quadrupole, single-bunch, insertion 2103
 
  • B. Singh, R.T. Fielder, I.P.S. Martin, G. Rehm
    Diamond, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  Funding: Diamond Light Source Ltd.
We report the results of the implementation of two vertical mini-beta and horizontally focusing optics at the Diamond light source, the first in August 2010 and the second in March 2011. Commissioning results of the two optics changes and experimental characterization of the optics are compared with the expected performance and theoretical modeling. The implications of a possible third customized optics are also investigated. 		 
 
WEPC048 Calibrating Transport Lines using LOCO Techniques quadrupole, dipole, simulation, focusing 2118
 
  • Y. Roblin
    JLAB, Newport News, Virginia, USA
  
  Funding: Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
With the 12GeV upgrade underway at CEBAF, there is a need to recharacterize the beamlines after the modifications made to it to accommodate running at higher energies. We present a linear perturbation approach to calibrating the optics model of transport lines. This method is adapted from the LOCO method in use for storage rings. We consider the effect of quadrupole errors, dipole construction errors as well as beam position monitors and correctors calibrations. The ideal model is expanded to first order in Taylor series of the quadrupole errors. A set of difference orbits obtained by exciting the correctors along the beamline is taken, yielding the measured response matrix. An iterative procedure is invoked and the quadrupole errors as well as beam position monitors and corrector calibration factors are obtained. Here we present details of the method and results of first measurements at CEBAF in early 2011 Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes 		 
 
WEPC050 New Optics for the SOLEIL Storage Ring injection, coupling, undulator, vacuum 2124
 
  • P. Brunelle, F. Briquez, A. Loulergue, O. Marcouillé, A. Nadji, L.S. Nadolski, M.-A. Tordeux, J.F. Zhang
    SOLEIL, Gif-sur-Yvette, France
  
  SOLEIL, the French 2.75GeV synchrotron light source is delivering photons to 24 beam lines and is presently equipped with 22 insertion devices (ID) including a high field and small gap in-vacuum wiggler*. This paper presents the continuous work performed to reduce the strong non linear effects of several IDs. On one side, the ID defaults have been precisely identified using on-beam measurements, and magnetic correction developments are going on, especially for the in-vacuum wiggler and for the 10m long HU640 undulator. On the other side, a new optics has been optimised in terms of beta-functions (at the ID location) and non linear dynamics in order to improve the injection efficiency and the beam lifetime in the presence of IDs. The modified optics has been used daily in operation since November 2010 and ensures a beam lifetime greater than 10h for a 400mA stored beam with the users ID configuration. In parallel, an extensive experimental optimization has been performed to prepare the operation with an additional quadrupole triplet that provides double low vertical beta functions in one long straight section that will accommodate two canted in-vacuum insertion devices**.
* O. Marcouillé et al., IPAC10, p. 3102 (2010).
** A. Loulergue et al., IPAC10, p. 2496 (2010). 		 
 
WEPC078 Non-linear Chromaticity Studies of the LHC at Injection octupole, dipole, injection, emittance 2199
 
  • E.H. Maclean, M. Giovannozzi, F. Schmidt, R.J. Steinhagen, E. Todesco, R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  The non-linear chromaticity of the LHC has been studied. Measurements of variation in tune with dp/p on both beams at injection optics are being compared with Q'' and Q''' as calculated with the LHC effective model. This model uses the best currently available measurements of magnetic field harmonics. An attempt is being made to optimize the b4 and b5 pool-pieces corrections in view of the corresponding chromaticity terms.  
 
WEPC079 Beta-beating in the Effective Model of the LHC Using PTC alignment, injection, closed-orbit, quadrupole 2202
 
  • M.C. Alabau Pons, F. Schmidt, R. Tomás
    CERN, Geneva, Switzerland
  • E.H. Maclean
    JAI, Oxford, United Kingdom
  
  An effective model of the LHC optics has been developed based on measurements of magnetic field, alignment errors and closed orbit. This model utilizes the Polymorphic Tracking Code with MAD-X as front-end to allow the inclusion of harmonics to an arbitrary order in thick lattice elements. Beta-beating calculations have been performed with this model at injection optics and at 3.5 TeV squeezed optics to 3.5 m beta-function at the interaction point. The model predictions are in remarkable agreement with the measurements performed in the 2010 LHC commissioning run.  
 
WEPC102 Recent Developments for Efficient 3D Space Charge Computations Based on Adaptive Multigrid Discretizations space-charge, simulation, brightness, injection 2253
 
  • G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • M.J. de Loos
    TUE, Eindhoven, The Netherlands
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
  
  Funding: Partly supported by BMBF under contract number 05K10HRC
Efficient and accurate space-charge computations are essential for the design of high-brightness charged particle sources. Recently a new adaptive meshing strategy based on multigrid was implemented in GPT and the capabilities were demonstrated. This new meshing scheme uses the solution of an intermediate step in the multigrid algorithm itself to define optimal mesh line positions. In this paper we discuss further developments of this adaptive meshing strategy. We compare the new algorithm with the current meshing scheme of GPT, where the mesh line positions are based upon the projected charge density. 		 
 
WEPC119 PYMAD – Integration of MADX in PYTHON simulation, status, background, lattice 2289
 
  • K. Fuchsberger, Y.I. Levinsen
    CERN, Geneva, Switzerland
  
  The de-facto standard software for modeling accelerator lattices at CERN is MADX (Methodical Accelerator Design), which is implemented and still maintained in the programming languages C and FORTRAN. For detailed processing, analysis and plotting of MADX results, other programming languages are often used. One very popular scripting language is PYTHON, which is widely used in the physics community and provides powerful numerical libraries and plotting routines. Therefore, access to MADX models from PYTHON is a common demand. Currently, several possible concepts for the realization of such a project are evaluated, including direct access to MADX via CYTHON (C extension of PYTHON) or the re-usage of the existing JMAD Java libraries, benefiting from the already available model-definitions. A first prototype is already in use and the release as an open source project is in preparation. This paper presents the concepts and the current status of the project, as well as some usage examples.  
 
WEPC120 Status of JMAD, the JAVA-API for MADX controls, status, lattice, feedback 2292
 
  • K. Fuchsberger, X. Buffat, Y.I. Levinsen, G.J. Müller
    CERN, Geneva, Switzerland
  
  MADX (Methodical Accelerator Design) is the de-facto standard software for modeling accelerator lattices at CERN. This feature-rich software package is implemented and still maintained in the programming languages C and FORTRAN. Nevertheless the controls environment of modern accelerators at CERN, e.g., of the LHC, is dominated by JAVA applications. A lot of these applications, for example, for lattice measurement and fitting, require a close interaction with the numerical models, which are all defined by the use of the proprietary MADX scripting language. To close this gap an API to MADX for the JAVA programming language (JMAD) was developed. JMAD was first presented to the public about one year ago. In the meantime, a number of improvements were done, and additional MADX features (e.g., tracking) were made available for JAVA applications. Additionally, the graphical user interface was improved, and the first release as open source software is in reach. This paper describes the current status and some new features of the project, as well as some usage examples.  
 
WEPC142 High Performance Web Applications for Particle Accelerator Control Systems controls, luminosity, collider, diagnostics 2322
 
  • G. Mazzitelli, C. Bisegni, P. Ciuffetti, G. Di Pirro, A. Stecchi
    INFN/LNF, Frascati (Roma), Italy
  • S. Calabrò, L.G. Foggetta
    IN2P3-CNRS, Orsay, France
  • L. Catani, F. Zani
    INFN-Roma II, Roma, Italy
  
  The integration of web technologies and applications has been one of the major trends for the development of new services for control systems of particle accelerators and large experimental apparatuses. Nowadays, high performance web technologies exhibit some features that would allow their deeper integration in a control system and their employment in developing control system's core components. In this paper we discuss the results of preliminary investigations of a new paradigm for a particle accelerator control system and associated machine data acquisition system based on a synergic combination of network distributed cache memory and a non-relational key/value database. Storage speed, network memory data retrieve throughput and database queries execution, as well as scalability and redundancy of the systems, are presented and critically reviewed.  
poster icon Poster WEPC142 [8.902 MB]  
 
WEPO031 The Magnetic Model of the LHC during Commissioning to Higher Beam Intensities in 2010-2011 injection, quadrupole, dipole, sextupole 2466
 
  • L. Deniau, N. Aquilina, L. Fiscarelli, M. Giovannozzi, P. Hagen, M. Lamont, G. Montenero, R.J. Steinhagen, M. Strzelczyk, E. Todesco, R. Tomás, W. Venturini Delsolaro, J. Wenninger
    CERN, Geneva, Switzerland
  
  The Field Description of the Large Hadron Collider (FiDeL) model is a set of semi-empirical equations linking the magnets behaviours established from magnetic measurements to the magnetic properties of the machine observed through beam measurements. The FiDeL model includes the parameterization of static components such as magnets residual magnetization, persistent currents, hysteresis and saturation as well as the decay and snap-back dynamic components. In the present paper, we outline the relationship between the beam observables (orbit, tune, chromaticity) and the model components during the commissioning to higher beam intensities in 2010-2011, with an energy of 3.5 TeV per beam. The main relevant issues are (i) the operation at 2 A/s and 10 A/s ramp rate and their influence on chromatic correction, (ii) the beta beating and its relation to the knowledge of the resistive quadrupoles transfer functions and (iii) the observed tune decay at injection energy and its possibles origins.  
 
WEPS030 Ion Optics Alignment in the Electrostatic Double Storage Ring DESIREE alignment, quadrupole, ion, storage-ring 2547
 
  • P. Löfgren, M. Blom, F. Hellberg, L. Liljeby, A. Simonsson
    MSL, Stockholm, Sweden
  • P. Reinhed
    Stockholm University, Stockholm, Sweden
  
  DESIREE is a cryogenic electrostatic double storage ring under construction at Stockholm University. The two rings have similar circumference, 8.8 m and a common straight section for merged beam experiments. In each ring the ions are guided by two 160° cylindrical deflectors and four 10° deflectors and focused by four quadrupole doublets. In terms of ion optics alignment the quadrupoles are the most important factor for the ion beam acceptance and the goal is to align all quadrupoles with precision of 0.1 mm. DESIREE is constructed as a double walled cryostat with an inner and an outer vacuum chamber. All optical elements are mounted directly on the bottom of the inner chamber. For positioning of the ion optics, the bottom plate is prepared with a number of footprints where each footprint consists of four small machined surfaces that define the height and two alignment holes that define the lateral position. The optical elements were aligned on the bottom plate using a portable measuring device in combination with a level instrument. In this work we describe the alignment procedure in detail and report on the overall precision obtained and the consequence for the ion beam.  
 
WEPS086 Three-lens Lattices for Extending the Energy Range of Non-scaling FFAGs lattice, closed-orbit, synchrotron, quadrupole 2709
 
  • S.J. Brooks
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  In this paper it is found that a three-quadrupole focussing system can be morphed continuously through FFD, FDF and DFF variants and back again while maintaining stable optics and even keeping the two transverse tunes constant. This relates to non-scaling FFAGs, where the magnet gradients define both the focussing and the variation of the field with momentum as the closed orbit sweeps across it. A two-lens focussing system cannot change the sign of either gradient without becoming unstable, meaning non-scaling FFAGs built with such a lattice eventually encounter too large a magnetic field at low energies. However, a theoretical system of magnet field variations using three lenses, with a potentially unlimited energy range and fixed tunes is presented here.  
 
WEPZ013 Design Status of LHeC Linac-Ring Interaction Region proton, electron, quadrupole, dipole 2796
 
  • R. Tomás, J.L. Abelleira, S. Russenschuck, F. Zimmermann
    CERN, Geneva, Switzerland
  • N.R. Bernard
    UCLA, Los Angeles, California, USA
  
  The ECFA-CERN-NuPECC design study for a Large Hadron electron Collider (LHeC) based on the LHC, considers two options, using a ring accelerator like LEP on top of the LHC or adding a recirculating energy-recovery linac tangential to the LHC. In order to obtain the required luminosity with an e- beam from a linac, with average lepton beam current limited to a few mA, reaching the smallest possible proton beam size is essential. Another constraint is imposed by the need to separate e- and p beams after the collision without losing too much luminosity from a crossing angle. A further constraint is that the ep collision should occur simultaneously to pp collisions at other LHC interaction points such that the second LHC proton beam must be accommodated in the interaction region too. We present a conceptual layout using detector-integrated combination-separation dipoles and challenging Nb3Sn technology quadrupoles for focusing the colliding proton beam and providing a low-field “hole” to accommodate both the non-colliding proton beam and the lepton beam, and the optics for all three beams. We discuss synchrotron radiation fluxes and the chromatic correction for the lepton final focus.  
 
THPPA01 EPS-AG Sacherer Prize: Beam Optics Developments for SPS, RHIC, LHC, CLIC and ATF2 resonance, sextupole, dipole, extraction 2894
 
  • R. Tomás
    CERN, Geneva, Switzerland
  
  Highlights of linear and nonlinear optics studies are presented from various accelerators. At the LHC, optics correction is of critical importance to guarantee safe beam operation. Preparation for LHC optics measurements and corrections has been a major activity during the last decade. In particular, SPS and RHIC have served as excellent research and development machines to test new techniques and instrumentation, such as the measurement of resonance driving terms with and without AC dipoles. Together with a meticulous field quality specification, a careful installation strategy and an elaborate magnet model, these efforts have paid off in the LHC, where a record low beta-beating for hadron colliders below 10% has been achieved. Looking further into the future, the performance of the Final Focus System (FFS) is of critical importance for a future linear collider like CLIC, since it determines the IP beam spot sizes. The large chromatic aberrations required the development of novel non-linear optimization methods. Such techniques have successfully increased the CLIC design luminosity by 70% and an experimental test has been proposed for ATF2 to halve the design IP beam spot sizes.  
slides icon Slides THPPA01 [1.514 MB]  
 
THPC002 Implementation of a Low-Emittance Optics for the LNLS UVX Storage Ring emittance, quadrupole, lattice, storage-ring 2907
 
  • F. H. de Sá, L. Liu, X.R. Resende
    LNLS, Campinas, Brazil
  
  In this report we describe the theoretical optimization and implementation of a low-emittance optics for the LNLS UVX storage ring. The emittance is reduced by letting the dispersion be distributed everywhere while keeping the low vertical beta feature. The optimization strategy is based on a series of quadrupole strength scans and selection of points satisfying a number of criteria. The new mode reduces the emittance from 100 nm.rad to 40 nm.rad, including the effects of the already installed insertion devices, and keeps the working point in the same quadrant as the present operation BBY6T mode. Tests have shown a reduction of approximately 20% in the horizontal and vertical beam sizes in the middle of the dipoles, in agreement with the theoretical emittance reduction.  
 
THPC012 Mitigating the Pertubations Caused by U 180 at the Metrology Light Source undulator, dipole, quadrupole, focusing 2930
 
  • P.O. Schmid, D.B. Engel, J. Feikes, M. Ries, G. Wüstefeld
    HZB, Berlin, Germany
  
  The Metrology Light Source is equipped with an electromagnetic undulator with a period length of 180 mm. User requests demand operation of this undulator in a wide energy range from 100 MeV through 629 MeV for user and dedicated low alpha modes. Mitigating the pertubations caused by the undulator to an acceptable level for all user requests, requires each quadrupole in the lattice to be powered individually. To what extend this recently implemented capability allows the restoration of the main properties of the machine optics for various settings of the undulator is presented in this document.  
 
THPC014 Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring cavity, focusing, radiation, electron 2936
 
  • G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries
    HZB, Berlin, Germany
  
  A scheme is discussed, where short and long bunches can be stored simultaneously in the BESSY II storage ring. With recent developments in sc-rf cavity technology it becomes possible, to install high gradient cavities in electron storage rings. With an appropriate choice of these cavities stable fixed points with different rf-voltage gradients are available, leading to different zero current bunch lengths. For BESSY II, we discuss the simultaneously storage of bunches with rms-lengths of 2 ps and 15 ps at high beam intensities. Additionally, in a low alpha optics sub-ps and ps-bunches are possible and a double bucket optics can be set up to store the two types of beams simultaneously on different orbits. Ultra-short and long bunches can be supplied to the users, separated by slightly different orbits.  
 
THPC020 PETRA III Upgrade undulator, sextupole, focusing, single-bunch 2948
 
  • K. Balewski, M. Bieler, J. Keil, A. Kling, G.K. Sahoo, R. Wanzenberg
    DESY, Hamburg, Germany
  
  PETRA III, the new third generation light source at DESY, has been running as a user facility since middle of 2010. All 14 undulator beam lines have been commissioned and up to 12 of them are currently in operation. However, already during the planning phase of PETRA III it turned out that the number of beamlines will not be sufficient to fulfill the request for beam time. The pressure to add more beamlines to PETRA III even increased after the decision to shut down DORIS III at the end of 2012. To increase the number of experimental stations two additional halls will be built each housing 5 additional beam lines and about 100 m of the accelerator close to each of the new buildings will be completely remodeled to install additional undulators. The upgrade has been formally approved and at present should be accomplished during a 6 month shut down in 2013. In this paper the layout of the upgraded accelerator will be shown. The impact of the upgrade on machine performance has been studied both theoretically and experimentally and the results of these studies will be presented.  
 
THPC026 Low Momentum Compaction Optics for Elettra emittance, lattice, quadrupole, sextupole 2963
 
  • E. Karantzoulis, A. Carniel, S. Krecic
    ELETTRA, Basovizza, Italy
  
  The DBA optics lattice of Elettra, the third generation Italian light source is closer to DBA minimum emittance condition than any other similar lattice. At the same time, although the lattice is also optimized for large acceptance, it is very inflexible to any changes like the reduction of the momentum compaction (very desirable to the IR and SR-FEL beam lines). Nevertheless a solution has been found and consists in abandoning the achromat condition and reversing the polarity of some quadrupole and sextupole families. This special optics and its applications to Elettra are presented and discussed.  
 
THPC059 Recent Improvements to the Lattices for the MAX IV Storage Rings storage-ring, lattice, injection, dipole 3029
 
  • S.C. Leemann
    MAX-lab, Lund, Sweden
  
  Construction of the MAX IV facility started early this year. The facility will include two storage rings for the production of synchrotron radiation. The 3 GeV ring will house insertion devices for the production of x-rays while the 1.5 GeV ring will serve UV and IR users. Recently, the lattices for the storage rings in the MAX IV facility were updated. In the 3 GeV storage ring the vertical beam size in the long straights has been reduced. The lattice of the 1.5 GeV storage ring has been updated to take into account first results from detailed magnet and vacuum system designs. Additionally, a new injection method to facilitate commissioning of the storage rings has been studied. This paper summarizes the changes made in the lattices and the effect of these modifications.  
 
THPC061 Comparison of Linear Optics Correction Means at the SLS quadrupole, betatron, storage-ring, closed-orbit 3032
 
  • M. Aiba, M. Böge, J.T.M. Chrin, N. Milas, T. Schilcher, A. Streun
    PSI, Villigen, Switzerland
  
  The experimental determination of linear optics is a fundamental prerequisite to achieving a high performance storage ring. In order to further enhance SLS performance and to simulataneously reveal the limitations of the various techniques, we perform a systematic study of linear optics optimization using various independent methods. These include an analysis of the orbit reponse (LOCO), turn-by-turn data, and the response of the tune, whose correction is accomplished using the standard SLS procedure of varying the quadrupole strengths. A comparison of results from these procedures, which use fully independent observables, provides us with a valuable cross-check. For example, the betatron phase advances between BPMs, which is independent of BPM calibration, confirms the optics correction as determined from LOCO. The linear optics are hence better optimized, and these procedures, LOCO in particular, further serve to expose any previously hidden mis-calibration of parameters e.g. from BPMs and corrector magnets. Systematic errors from turn-by-turn data could also be vastly reduced by a better synchronization of the BPM triggers with the electron beam.  
 
THPC103 Beam Dynamics Study of X-band Linac Driven X-ray FELs linac, simulation, electron, FEL 3128
 
  • Y. Sun, C. Adolphsen, C. Limborg-Deprey, T.O. Raubenheimer, J. Wu
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by the DOE under Contract DE-AC02-76SF00515
Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly. 		 
 
THPC155 Modification of the BESSY II Optic for the Implementation of a Small Gap Undulator undulator, cryogenics, quadrupole, sextupole 3251
 
  • J. Bahrdt, K.B. Bürkmann-Gehrlein, V. Dürr, W. Frentrup, A. Gaupp, A. Jankowiak, P. Kuske, J. Rahn, M. Scheer, P.O. Schmid, G. Wüstefeld
    HZB, Berlin, Germany
  
  At BESSY there is an increasing demand for photons in the range from 60 eV to 8 keV available at the same experimental station. The photons will be produced by a combination of two adjacent undulators, one of them will be a small period cryogenic undulator. Several optics schemes for the 1.7 GeV BESSY II storage ring are discussed to install the undulators. Two types of straight sections exist. A high beta straight with betaxmin=15 m and betaymin=4.5 m and a low beta straight with betaxmin=betaymin=1 m. We discuss the present plan, which clearly favours a small detuning of an existing low beta straight to shift the low beta waist to the centre of the low gap undulator, with only minor impact to the machine.  
 
THPC156 Performance of the PETRA III APPLE II Undulator undulator, multipole, storage-ring, closed-orbit 3254
 
  • J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer
    HZB, Berlin, Germany
  • K. Balewski, J. Keil, A. Schöps, M. Tischer
    DESY, Hamburg, Germany
  
  A 5m-long APPLE II undulator has been built in collaboration between Helmholtz-Zentrum Berlin and DESY Hamburg. Magnetic field measurements after the final shimming in the laboratory are presented. The device has been installed in the storage ring and machine studies have been performed. The tune shifts in the elliptical and the inclined mode are in agreement with predictions from theory. The dynamic field integrals have successfully been minimized in the storage ring with so-called L-shims (rectangular iron sheets) which are placed at the undulator center at the magnet edges.  
 
THPS030 Layout and Optics of the MedAustron High Energy Beam Transfer Line proton, extraction, synchrotron, quadrupole 3484
 
  • U. Dorda, P.J. Bryant
    CERN, Geneva, Switzerland
  • M. Benedikt
    EBG MedAustron, Wr. Neustadt, Austria
  
  The MedAustron accelerator complex, which is currently in its final design stage at CERN, is based on the optical principles developed within the Proton Ion Medical Machine study (PIMMS) [bryantpimms]. This paper describes how these principles are practically applied in the layout and optics of the High Energy Beam Transfer line (HEBT) of the MedAustron accelerator facility. Special attention is directed to the optics of the gantry which is designed to fit into the PSI gantry-2 hardware layout, which is foreseen to be copied in collaboration with PSI.  
 
THPS049 Feasibility Study of a CERN PS Injection at 2 GeV injection, kicker, septum, vacuum 3535
 
  • J. Borburgh, S. Aumon, W. Bartmann, S.S. Gilardoni, B. Goddard, L. Sermeus, R.R. Steerenberg
    CERN, Geneva, Switzerland
  
  In the framework of the potential CERN PS Booster (PSB) energy upgrade, a study was initiated to look into the possibilities and constraints to inject protons into the PS at kinetic energies up to 2 GeV, for LHC type beams and other (high intensity) beams. This paper highlights the identified bottlenecks and potential solutions and addresses the resulting requirements for the hardware in the transfer line and injection region of the PS. In conjunction with the proposed upgrade of the PSB-PS transfer line hardware the optics can be changed for different cycles. Optics solutions optimized for the different requirements of LHC type and other beams are presented.  
 
THPS053 Results from the HiRadMat Primary Beam Line Commissioning beam-losses, proton, controls, instrumentation 3547
 
  • C. Heßler, M. Arruat, J. Bauche, K. Bestmann, J. Blanco, N. Conan, K. Cornelis, I. Efthymiopoulos, H. Gaillard, B. Goddard, D. Grenier, G.G. Gros, A. Habert, L.K. Jensen, V. Kain, G. Le Godec, M. Meddahi, S. Pelletier, P. Pepinster, B. Puccio, C. Theis, P. Trilhe, G. Vandoni, J. Wenninger
    CERN, Geneva, Switzerland
  
  The High Radiation to Materials facility (HiRadMat) is a new experimental area at CERN, for studies of the impact of high-intensity pulsed beams on accelerator components and materials. The beam is delivered from the SPS by a new primary beam line, which has been constructed during the 2010/11 winter technical stop. The paper summarizes the construction phase and describes the results from the beam line commissioning in spring 2011. Beam parameter and aperture measurements are presented, as well as steering tests. A special emphasis has been put on the handling of the exceptionally flexible beam line optics in the control system.  
 
THPS081 Design Choices of the MedAustron Nozzles and Proton Gantry based on Modeling of Particle Scattering scattering, proton, vacuum, dipole 3621
 
  • M. Palm
    CERN, Geneva, Switzerland
  • M. Benedikt, A. Fabich
    EBG MedAustron, Wr. Neustadt, Austria
  • M. Palm
    ATI, Wien, Austria
  
  MedAustron, the Austrian hadron therapy center is currently under construction. Irradiations will be performed using active scanning with a proton or carbon ion pencil beam which is subject to scattering in vacuum windows, beam monitors and air gap. For applications where sharp lateral beam penumbras are required in order to spare critical organs from unwanted dose, scattering should be minimal. A semi-empirical scattering model has been established to evaluate beam size growth at the patient due to upstream scattering. Major design choices for proton gantry and nozzle based on the scattering calculations are presented.  
 
THPS090 Development of the Pulse Radiolysis System with a Supercontinuum Radiation using Photonic Crystal Fiber laser, radiation, electron, gun 3645
 
  • K.B. Ogata, R. Betto, Y. Hosaka, Y. Kawauchi, K. Sakaue, T. Suzuki, M. Washio
    RISE, Tokyo, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • R. Kuroda
    AIST, Tsukuba, Ibaraki, Japan
  
  Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690
In usage of radiation, it is important to study the process of chemical effects of ionizing radiation in a material. Pulse radiolysis is a method to trace these rapid initial chemical reactions by ionizing radiation. As a pump beam, we are using 5MeV electron beam produced from the S-band photo cathode RF-Gun. In nanosecond timescale pulse radiolysis, it is required the stable probe light of a broad spectrum. And especially in picosecond timescale pulse radiolysis, probe light should have short pulse width to use stroboscopic method. Therefore, in order to develop a wide range of timescale experimental system, we have been developing a Supercontinuum (SC) light as a probe light, which is generated by nonlinear optical process of short pulse IR laser in photonic crystal fiber (PCF). As a result, the SC light spectrum is broad enough to use as a probe light. Then we tried to measure the absorption spectrum of hydrated electron by SC light, we successfully observed good signal-noise ratio data both nanosecond and picosecond experiment with unified pulse　radiolysis system. In this conference, we will report details of these results and future prospects. 		 
 
THPZ012 Luminosity Enhancement and Performance in BEPCII luminosity, background, quadrupole, coupling 3708
 
  • Q. Qin, J. Cao, J. Cheng, Y.L. Chi, H. Dong, Z. Duan, D. Ji, W. Kang, S.P. Li, L. Ma, H. Qu, C.H. Wang, G.W. Wang, J.Q. Wang, X.H. Wang, Y. Wei, J. Xing, G. Xu, C.H. Yu, J. Yue, C. Zhang, Y. Zhang
    IHEP Beijing, Beijing, People's Republic of China
  
  The Beijing Electron Positron Collider (BEPC) was upgraded to a factory-like machine –- BEPCII, during last several years. From last November, the BEPCII was commissioned again for its luminosity. Efforts on optics correction including optimizing the strengths of superconducting quadrupoles near the IP, orbits correction concerning beam energy, etc, make the transvers tunes possible to move very close to half integer, bringing a big luminosity increase. The background of the detector is also reduced with beam commissioning, and finally fit the requirements of data taking. Further luminosity commissioing, including coupling optimization, beta-waist tuning, was carried on, and the luminosity reached 6.49·1032 cm-2 s-1 during routine operation. Some measures of luminosity enhancement and the luminosity related accelerator physics issues will be discussed.  
 
THPZ013 A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities cavity, insertion, luminosity, dynamic-aperture 3711
 
  • R. De Maria, S.D. Fartoukh
    CERN, Geneva, Switzerland
  
  The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme*.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings. 		 
 
THPZ014 LHeC Lattice Design dipole, lattice, insertion, electron 3714
 
  • M. Fitterer, O.S. Brüning, H. Burkhardt, B.J. Holzer, J.M. Jowett, K.H. Meß, T. Risselada
    CERN, Geneva, Switzerland
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  • A.-S. Müller
    KIT, Karlsruhe, Germany
  
  The Large Hadron Electron Collider (LHeC) aims at lepton-proton and lepton-nucleus collisions with centre of mass energies of 1-2 TeV at ep luminosities in excess of 1033 cm-2 s-1. We present here a lattice design for the electron ring option, which meets the design parameters and also the constraints imposed by the integration of the new electron ring in the LHC tunnel.  
 
THPZ016 Interaction Region Design for a Ring-Ring LHeC quadrupole, electron, luminosity, proton 3720
 
  • L.N.S. Thompson, R. Appleby
    UMAN, Manchester, United Kingdom
  • N.R. Bernard
    UCLA, Los Angeles, California, USA
  • M. Fitterer
    KIT, Karlsruhe, Germany
  • B.J. Holzer
    CERN, Geneva, Switzerland
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  • P. Kostka
    DESY Zeuthen, Zeuthen, Germany
  • L.N.S. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Using one of the LHC's proton beams, an electron beam of relatively low energy and moderately high intensity provides high luminosity TeV-scale e-p collisions at one of the LHC interaction points, running simultaneously with existing experiments. Two designs are studied; an electron ring situated in the LHC tunnel, and an electron linac. The focus of this paper is on the ring design. Designing an e-p machine presents interesting accelerator physics and design challenges, particularly when considering the interaction region. These include coupled optics, beam separation and unconventional mini-beta focusing schemes. Designs are constrained by an array of interdependent factors, including beam-beam interaction, detector dimensions and acceptance, luminosity and synchrotron radiation. Methods of addressing these complex issues are discussed. The current designs for the LHeC Ring-Ring interaction region and long straight section are presented and discussed, in the context of the project goals and design challenges encountered. Future developments and work are also discussed.  
 
THPZ029 Principles for Generation of Time-dependent Collimator Settings during the LHC Cycle injection, collimation, controls, beam-losses 3753
 
  • R. Bruce, R.W. Assmann, S. Redaelli
    CERN, Geneva, Switzerland
  
  The settings of the LHC collimators have to be changed during the cycle of injection, ramp and squeeze to account for variations in the orbit, beam size and normalized distance to the beam center. We discuss the principles for how the settings are calculated and show a software tool that computes them as time-dependent functions from beam-based data and theoretical optics models.  
 
THPZ033 Operational Experience and Performance of the LHC Collimator Controls System controls, collimation, monitoring, collider 3765
 
  • S. Redaelli, A. Masi
    CERN, Geneva, Switzerland
  
  In order to handle stored energies up to 360 MJ, the LHC relies on a collimation system that consists of 100 movable collimators. Compared to other accelerator, the complexity of this system is unique: more than 400 motors and about 600 interlocked position sensors must be controlled in all the machine phases in order to ensure the cleaning and machine protection roles of the system. In this paper, the controls system and the setting management are presented and the operational experience accumulated in the 2 first years of operation is discussed, focussing in particular on failure and availability statistics during the LHC operation.